IFIBA   22255
INSTITUTO DE FISICA DE BUENOS AIRES
Unidad Ejecutora - UE
artículos
Título:
Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
Autor/es:
PIERRE AUGER COLLABORATION, ..., R.PIEGAIA,
Revista:
ASTROPARTICLE PHYSICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2009 vol. 31, p. 399 - 408
ISSN:
0927-6505
Resumen:
From direct observations of the longitudinal development of ultra-high
energy air showers performed with the Pierre Auger Observatory, upper
limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the
fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV ,
respectively. These are the first experimental limits on ultra-high
energy photons at energies below 10 EeV. The results complement
previous constraints on topdown models from array data and they reduce
systematic uncertainties in the interpretation of shower data in terms
of primary flux, nuclear composition and proton-air cross-section.